In Portuguese, it means someone who hides their flaws and pretends to be innocent, and has a behavior opposite from what they really are. Someone who hides their intentions, and pretends to be a fool. It's someone who fools you, who fakes it, being quiet, but he's always up to something.

That detective pretended to be sonso in order to find out information.

He claims to be faithful to his wife, but he is very sonso. He keeps looking at other people's wives.

She said she didn't see anything, but she was there, running her mouth with the other ones... she is very sonsa!

In Portuguese, it means someone who hides their flaws and pretends to be innocent, and has a behavior opposite from what they really are. Someone who hides their intentions, and pretends to be a fool. It's someone who fools you, who fakes it, being quiet, but he's always up to something.

That detective pretended to be sonso in order to find out information.

He claims to be faithful to his wife, but he is very sonso. He keeps looking at other people's wives.

She said she didn't see anything, but she was there, running her mouth with the other ones... she is very sonsa!